Micro device and micro device display apparatus

ABSTRACT

A micro device includes an epitaxial structure and a light guide structure. The epitaxial structure has a top surface. The light guide structure is disposed on the top surface, and the light guide structure includes a connecting portion and a covering portion. The connecting portion is disposed on an edge of the epitaxial structure and extends along a sidewall of the epitaxial structure. The covering portion is disposed on the top surface and connected to the connecting portion. A width of the connecting portion at the edge of the epitaxial structure is smaller than a width away from the top surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of and claims thepriority benefit of U.S. application Ser. No. 16/212,694, filed on Dec.7, 2018, now allowed, which claims the priority benefit of U.S.provisional application Ser. No. 62/607,325, filed on Dec. 19, 2017 andTaiwan application serial No. 107119257, filed on Jun. 5, 2018. Theentirety of each of the above-mentioned patent applications is herebyincorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION Field of the Invention

The invention is related to a semiconductor structure, and particularlyto a structure with micro device.

Description of Related Art

In current techniques, transfer of micro light emitting diode (LED) isconducted mainly through the means of electrostatic force or magneticforce to transfer the micro LED on a carrier to a receiving substrate.Typically, the micro LED is held through a holding structure such thatthe micro LED can be picked up more easily from the carrier as well asdelivered and transferred to be placed on the receiving substrate;moreover, the quality of the micro LED is not easily affected by otherfactors through use of the holding structure to hold the micro LED inthe transferring process. However, the size and shape of a contact areabetween the holding structure and the micro LED affect the yield rate ofdelivery and transfer of the micro LED. In light of the above, it hasbecome an important issue for related industries to find out how to makethe holding structure to temporarily hold the micro LED and make themicro LED to be delivered and transferred between the carrier and thereceiving substrate more easily and effectively.

SUMMARY OF THE INVENTION

The invention provides a micro device which has better light-emittingefficiency.

According to the invention, a micro device includes an epitaxialstructure and a light guide structure. The epitaxial structure has a topsurface. The light guide structure is disposed on the top surface, andthe light guide structure includes a connecting portion and a coveringportion. The connecting portion is disposed on an edge of the epitaxialstructure and extends along a sidewall of the epitaxial structure. Thecovering portion is disposed on the top surface and connected to theconnecting portion. A width of the connecting portion at the edge of theepitaxial structure is smaller than a width away from the top surface.

According to an embodiment of the invention, the width of the connectingportion away from the top surface gradually increases.

According to an embodiment of the invention, an outer contour of theconnecting portion is a curved contour.

According to an embodiment of the invention, a central width of thecovering portion is larger than a width of the connecting portion on thecorresponding edge of the top surface.

According to an embodiment of the invention, the covering portion has aplurality of inflection points, and a width of the covering portion isgradually increased from the inflection points to the connectingportion.

According to an embodiment of the invention, a central width of thecovering portion is smaller than a width of the connecting portion onthe corresponding edge of the top surface.

According to an embodiment of the invention, a width of the coveringportion is gradually increased toward the connecting portion.

According to an embodiment of the invention, micro device furthercomprises a light guide layer connected to the top surface of theepitaxial structure. An area of the light guide layer is less than orequal to an area of the top surface of the epitaxial structure, and thearea of the light guide layer on the top surface of the epitaxialstructure is larger than an area of the light guide structure on thelight guide layer.

According to an embodiment of the invention, the connecting portion doesnot contact the sidewall of the epitaxial structure.

According to an embodiment of the invention, the covering portion has apatterned surface, and the connecting portion has a flat surface.

According to an embodiment of the invention, a ratio of a verticalheight of the connecting portion to a vertical height of the epitaxialstructure is less than or equal to 0.3.

According to an embodiment of the invention, a ratio of a horizontalwidth of the connecting portion to a horizontal width of a epitaxialstructure is less than or equal to 0.3.

According to an embodiment of the invention, the epitaxial structurecomprises a first-type semiconductor layer, a second-type semiconductorlayer and a light-emitting layer. The first-type semiconductor layer hasthe top surface. The light-emitting layer is located between thefirst-type semiconductor layer and the second-type semiconductor layer.The top surface of the first-type semiconductor layer is relatively farfrom the light-emitting layer, and the connecting portion directlycovers a peripheral surface of the first-type semiconductor layer and aperipheral of the light-emitting layer.

According to the invention, a micro device display apparatus includes acircuit substrate and at least one micro device. The micro device isdisposed on the circuit substrate and includes an epitaxial structureand a light guide structure. The epitaxial structure has a top surface.The light guide structure is disposed on the top surface, and the lightguide structure includes a connecting portion and a covering portion.The connecting portion is disposed on an edge of the epitaxial structureand extends along a sidewall of the epitaxial structure. The coveringportion is disposed on the top surface and connected to the connectingportion. A width of the connecting portion at the edge of the epitaxialstructure is smaller than a width away from the top surface.

Based on the above, in the design of the micro device of the invention,the connecting portion of the light guide structure is disposed on theedge of the epitaxial structure and extending along the sidewall of theepitaxial structure. In particular, the width of the connecting portionat the edge of the epitaxial structure is smaller than the width awayfrom the top surface, thereby improving the side light-emittingefficiency of the micro device. Therefore, in addition to the coveringportion that can effectively raise a forward light-emitting efficiencyof the micro device, the connecting portion can also raise a sidelight-emitting efficiency of the micro device, thereby improving thelight-emitting efficiency of the micro device.

In order to make the aforementioned features and advantages of thedisclosure more comprehensible, embodiments accompanying figures aredescribed in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic top view of a structure with micro deviceaccording to a first embodiment of the invention.

FIG. 1B is a schematic cross-sectional view of the structure with microdevice in FIG. 1A.

FIG. 2A is a schematic top view of a structure with micro deviceaccording to a second embodiment of the invention.

FIG. 2B is a schematic cross-sectional view of the structure with microdevice in FIG. 2A.

FIG. 3 is a schematic top view of a structure with micro deviceaccording to a third embodiment of the invention.

FIG. 4A is a schematic top view of a structure with micro deviceaccording to a fourth embodiment of the invention.

FIG. 4B is a schematic cross-sectional view of the structure with microdevice in FIG. 4A.

FIG. 5 is a schematic top view of a structure with micro deviceaccording to a fifth embodiment.

FIG. 6A is a schematic top view of a structure with micro deviceaccording to a sixth embodiment of the invention.

FIG. 6B is a schematic cross-sectional view of the structure with microdevice in FIG. 6A.

FIG. 7 is a schematic top view of a structure with micro deviceaccording to a seventh embodiment of the invention.

FIG. 8 is a schematic top view of a structure with micro deviceaccording to an eighth embodiment of the invention.

FIG. 9 is a schematic top view of a structure with micro deviceaccording to a ninth embodiment of the invention.

FIG. 10 is a schematic cross-sectional view of a structure with microdevice according to a tenth embodiment of the invention.

FIG. 11 is a schematic cross-sectional view of a structure with microdevice according to an eleventh embodiment of the invention.

FIG. 12 is a schematic cross-sectional view of a structure with microdevice according to a twelfth embodiment of the invention.

FIG. 13 is a schematic cross-sectional view of a structure with microdevice according to a thirteenth embodiment of the invention.

FIG. 14 is a schematic cross-sectional view of a structure with microdevice according to a fourteenth embodiment of the invention.

FIG. 15 is a schematic cross-sectional view of a structure with microdevice according to a fifteenth embodiment of the invention.

FIG. 16 is a schematic cross-sectional view of a structure with microdevice according to a sixteenth embodiment of the invention.

FIG. 17 is a schematic cross-sectional view of a structure with microdevice according to a seventeenth embodiment of the invention.

FIG. 18 is a schematic cross-sectional view of a structure with microdevice according to an eighteenth embodiment of the invention.

FIG. 19 is a schematic cross-sectional view of a structure with microdevice according to a nineteenth embodiment of the invention.

FIG. 20 is a schematic cross-sectional view of a structure with microdevice transferred to a circuit substrate according to an embodiment ofthe invention.

FIG. 21 is a schematic cross-sectional view of a structure with microdevice transferred to a circuit substrate according to anotherembodiment of the invention.

FIG. 22 is a schematic cross-sectional view of a structure with microdevice transferred to a circuit substrate according to still anotherembodiment of the invention.

FIG. 23A is a schematic three-dimensional view of a micro deviceaccording to an embodiment of the invention.

FIG. 23B is a schematic side view of the micro device in FIG. 23A.

FIG. 24 is a schematic top view of a micro device according to anembodiment of the invention.

FIG. 25A is a schematic top view of a micro device according to anotherembodiment of the invention.

FIG. 25B is a schematic side view of the micro device in FIG. 25A.

FIG. 26A is a schematic top view of a micro device according to anotherembodiment of the invention.

FIG. 26B is a schematic side view of the micro device in FIG. 26A.

FIG. 27A is a schematic cross-sectional view of a micro device accordingto an embodiment of the invention.

FIG. 27B is a schematic cross-sectional view of a micro device accordingto another embodiment of the invention.

FIG. 28 is a schematic cross-sectional view of a micro device accordingto another embodiment of the invention.

FIG. 29 is a schematic cross-sectional view of a micro device accordingto another embodiment of the invention.

FIG. 30 is a schematic cross-sectional view of a micro device displayapparatus according to an embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

The embodiments of the invention describe the structure of micro device(e.g., micro LED and micro chip) that is ready to be picked up andtransferred to a circuit substrate. For example, a receiving substratemay be a display substrate, a light emitting substrate, a substratehaving functional element such as transistor or integrated circuit (ICs)or a substrate having metal redistribution line, but the invention isnot limited thereto. Although some embodiments of the invention focus onmicro LED containing p-n diode, it should be understood that theembodiments of the invention are not limited thereto. Some embodimentsmay be applied to other micro semiconductor devices, and the devices aredesigned in this manner to control execution of predetermined electronicfunction (e.g., diode, transistor, integrated circuit) or photonfunction (e.g., LED, laser).

FIG. 1A is a schematic top view of a structure with micro deviceaccording to a first embodiment of the invention. FIG. 1B is a schematiccross-sectional view of the structure with micro device in FIG. 1A. Itshould be indicated that a structure with micro device 100 in FIG. 1B isillustrated along line A-A′ of FIG. 1A.

Referring to FIG. 1A and FIG. 1B, the structure with micro device 100 inthe embodiment includes a substrate 120, at least one micro device 140(a plurality of micro devices are exemplified in FIG. 1A) and at leastone holding structure 160 (a plurality of holding structures areexemplified in FIG. 1A). The micro device 140 is disposed on thesubstrate 120. The micro device 140 has a top surface 141, a bottomsurface 142, a peripheral surface 143, a first-type electrode 144 and asecond-type electrode 145. The top surface 141 and the bottom surface142 are opposite to each other, and the top surface 141 is farther awayfrom the substrate 120 than the bottom surface 142. The peripheralsurface 143 connects the top surface 141 and the bottom surface 142. Theholding structure 160 is disposed on the substrate 120, and is notdirectly in contact with the first-type electrode 144 and thesecond-type electrode 145 of corresponding micro device 140. Each of theholding structures 160 includes at least one covering portion 163 (onecovering portion 163 is exemplified in FIG. 1A), at least one connectingportion (two connecting portions 162 a, 162 b are exemplified in FIG.1A) and at least one holding portion (two holding portions 161 a, 161 bare exemplified in FIG. 1A). The covering portion 163 is directly incontact with a partial top surface 141 of the micro device 140. Theconnecting portions 162 a and 162 b are respectively connected to thecovering portion 163 from two opposite edges SD1 and SD3 of the microdevice 140. The holding portions 161 a and 161 b connect the connectingportions 162 a and 162 b and extend to the substrate 120. As shown inFIG. 1A, two adjacent micro devices 140 are connected together throughthe holding portions 161 a and 161 b of the corresponding holdingstructure 160. Meanwhile, from a top view direction, the connectingportions 162 a and 162 b are extended along a horizontal direction D1parallel with the extending direction of the substrate 120 and connectedbetween the covering portion 163 and the holding portions 161 a and 161b, and width change of the connecting portions 162 a and 162 b isgradually increased from the two opposite edges SD1 and SD3 of the microdevice 140 to the corresponding holding portions 161 a and 161 b.

Specifically, the substrate 120 is a temporary substrate that may havefixity and flat surface such as a plastic substrate, a glass substrateor a sapphire substrate, the invention is not limited thereto. As shownin FIG. 1A, from the top view direction, the top surface 141 of themicro device 140 has four edges SD1, SD2, SD3, SD4 and four corners C1,C2, C3, C4 constructed along with the edges SD1, SD2, SD3, SD4. The edgeSD1 and the edge SD3 of the top surface 141 of the micro device 140 aredisposed opposite to each other, and the edge SD2 and the edge SD4 aredisposed opposite to each other. In the embodiment, the lengths of theedge SD1 and the edge SD3 are longer than the lengths of the edge SD2and the edge SD4. In other words, the counter of the micro device 140viewed from a top view direction is specifically a rectangular shape,the invention is not limited thereto. In other embodiments, the counterof the micro device 140 viewed from the top may be other suitable shapessuch as a trapezoidal shape or other suitable shapes. It should beindicated that, as shown in FIG. 1A, the top surface 141 of the microdevice 140 refers to the surface corresponding to the position of alight emitting layer 146 of the micro device 140.

In the embodiment, the first-type electrode 144 of the micro device 140is located on the top surface 141. In other words, the micro device 140of the embodiment is substantially a horizontal-type micro device.Certainly, in other embodiments that are not shown, it may be that thesecond-type electrode 145 is disposed on the top surface 141, theinvention is not limited thereto. Herein, the first-type electrode 144is, for example, a p-type electrode, and the second-type electrode 145is, for example, an n-type electrode. However, in other embodiments, thefirst-type electrode 144 may be an n-type electrode, and the second-typeelectrode 145 may be a p-type electrode, the invention provides nolimitation thereto. In other embodiments, the micro device 140 may be inthe form of a horizontal-type micro light emitting diode or other typesof micro light emitting diode. Herein, the micro device 140 is, forexample, a micro light emitting diode, and a largest size of the microdevice 140 is smaller than or equal to 100 μm so as to be subsequentlytransferred to be integrated and assembled to a heterogeneousintegrating system, including substrates of any size ranging from microdisplay to a display with large area. In other embodiments that are notshown, the micro device 140 may be a micro integrated circuit (microIC), a micro laser diode (micro LD) or a micro sensor and so on, theinvention provides no limitation thereto.

Referring to FIG. 1A, the connecting portion 162 a of the holdingstructure 160 is connected to one side of the covering portion 163 fromthe edge SD1 of the top surface 141 of the micro device 140, and thewidth change of the connecting portion 162 a of the holding structure160 is gradually increased from the edge SD1 of the micro device 140 tothe holding portion 161 a. The connecting portion 162 b of the holdingstructure 160 is connected to another side of the covering portion 163through the edge SD3 of the top surface 141 of the micro device 140, andthe width change of the connecting portion 162 b is gradually increasedfrom the edge SD3 of the micro device 140 to the holding portion 161 b.In other words, the connecting portion 162 a has a smallest width W1 onthe corresponding edge S1 of the top surface 141 of the micro device140, and the connecting portion 162 b has a smallest width W2 on thecorresponding edge SD3 of the top surface 141 of the micro device 140.Preferably, a ratio of the smallest widths W1 and W2 of the connectingportions 162 a and 162 b at the edges SD1 and SD3 to the lengths of thecorresponding edges SD1 and SD3 is in a range between 0.01 and 0.6. Whenthe ratio is smaller than 0.01, the holding structure 160 cannoteffectively hold the micro device 140, that is, the holding forceprovided by the holding structure 160 is not big enough. On thecontrary, when the ratio is larger than 0.6, the holding force providedby the holding structure 160 is too large, which causes that the microdevice 140 cannot be smoothly picked up from the substrate 120. Thesmallest widths W1 and W2 are, for example, smaller than or equal to 20μm. More specifically, from the top view direction, the outer contour ofthe connecting portions 162 a and 162 b of the holding structure 160 ofthe embodiment is a curved contour, which should not be construed as alimitation to the invention. It should be pointed out that the ratio ofthe orthogonal projection area of the holding structure 160 on the topsurface 141 to the surface area of the top surface 141 of the microdevice 140 is, for example, larger than or equal to 0.01 and smallerthan or equal to 0.6. When the ratio is smaller than 0.01, the holdingforce provided by the holding structure 160 is not big enough. When theratio is larger than 0.6, it is likely that the holding structure 160 isin contact with the first-type electrode 144, which subsequently affectsthe yield rate of transferring the micro device to a circuit substrate(not shown).

It should be indicated that, when the micro device 140 is picked up fromthe substrate 120, the force for picking up (e.g., press-down force orpull-up force) causes the holding structure 160 to break. Since thepositions of the smallest widths W1 and W2 of the connecting portions162 a and 162 b are at the edges SD1 and SD3 of the corresponding microdevice 140, it is possible that the breaking point of the holdingstructure 160 can be substantially located at or as close to the edgesSD1 and SD3 of the micro device 140 as possible, thereby reducing theproblem that the holding structure 160 is not completely broken orremained, such that the yield rate of delivery and transfer of the microdevice 140 can be improved.

In some embodiments, if the connecting portions 162 a and 162 b of theholding structure 160 directly cover one of or a plurality of cornersC1, C2, C3, C4 of the micro device 140, it is possible that theconnecting portions 162 a and 162 b can have the smallest width in thecovered corners C1, C2, C3, C4 or the corresponding edges SD1, SD2, SD3,SD4 (e.g., edges SD1, SD4 corresponding to corner C1), such that theyield rate of delivery and transfer of the micro device 140 can beimproved.

Further referring to FIG. 1A and FIG. 1B, in the embodiment, theconnecting portions 162 a and 162 b of the holding structure 160 arefurther directly in contact with the peripheral surface 143 of the microdevice 140, the invention is not limited thereto. From the top viewdirection, the covering portion 163 of the holding structure 160 iscontinuously connected to the top surface 141 of the micro device 140,and the width change of the covering portion 163 is gradually decreasedfrom the connecting portions 162 a and 162 b to a center 141P of the topsurface 141 of the micro device 140. In other words, a central width W3of the covering portion 163 is smaller than the width (i.e., smallestwidths W1, W2) of the connecting portions 162 a and 162 b at thecorresponding edges SD1 and SD3 of the top surface 141. In this manner,during the exposure and etching process for forming the holdingstructure 160, even if a slight shift is occurred unexpectedly, e.g.,shift to the direction D1, the holding structure 160 can still bedisposed on the top surface 141 of the micro device 140 without beingshifted to other position, and the connecting portions 162 a and 162 bof the holding structure 160 can have the narrowest widths W1 and W2between the edges SD1 and SD3 of the micro device 140 and the holdingportions 161 a and 161 b, such that the process window of the holdingstructure 160 can be enhanced.

In the embodiment, the holding portions 161 a and 161 b of the holdingstructure 160 are directly in contact with the substrate, but theinvention is not limited thereto. Additionally, there may be nocomponent provided between the micro device 140 and the substrate 120(e.g., there is air space/gas space between the micro device 140 and thesubstrate 120 in a non-vacuum state), which is still within theprotection range of the invention.

It is to be explained that, the following embodiment has adoptedcomponent notations and part of the contents from the previousembodiment, wherein the same notations are used for representing thesame or similar components, and descriptions of the same technicalcontents are omitted. The descriptions regarding the omitted part may bereferred to the previous embodiments, and thus are not repeated herein.

FIG. 2A is a schematic top view of a structure with micro deviceaccording to a second embodiment of the invention. FIG. 2B is aschematic cross-sectional view of the structure with micro device inFIG. 2A. It should be pointed out that a structure with micro device 200in FIG. 2B is illustrated along line B-B′ of FIG. 2A. The structure withmicro device 200 in the embodiment is similar to the structure withmicro device 100 in the first embodiment, and the difference between thetwo is that the structure with micro device 200 further includes atleast one buffering structure (a plurality of buffering structures 280a, 280 b are exemplified in FIG. 2A). The buffering structures 280 a and280 b are disposed between the holding portions 261 a and 261 b of theholding structure 260 and the substrate 120, wherein the holdingportions 261 a and 261 b are connected to the substrate 120 through thebuffering structures 280 a and 280 b.

Specifically, the buffering structures 280 a and 280 b are far away fromthe micro device 140; that is, the buffering structures 280 a and 280 bare not directly in contact with the micro device 140. Two oppositesides of the buffering structures 280 a and 280 b are respectivelydirectly in contact with a holding structure 260 and the substrate 120.In other words, the holding structure 260 of the embodiment is notdirectly in contact with the substrate 120 but connected to thesubstrate 120 through the buffering structures 280 a and 280 b. Herein,the orthonogal projection of the holding structure 260 on the substrate120 overlaps the orthogonal projection of the buffering structures 280 aand 280 b on the substrate 120. Preferably, in a unit area U, a ratio ofthe orthogonal projection area of the buffering structures 280 a and 280b on the substrate 120 to the orthogonal projection area of the holdingstructure 260 on the substrate 120 is, for example, in a range between0.2 and 0.9. When the ratio is smaller than 0.2, the buffering force ofthe buffering structure is not big enough; when the ratio is larger than0.9, the connection between the buffering structure and the holdingstructure is too big and affects the subsequent picking-up process. Morepreferably, in the unit area U, a ratio of the orthogonal projectionarea of the buffering structures 280 a and 280 b on the substrate 120 tothe orthogonal projection area of the holding portions 261 a and 261 bcorresponding to the position of the buffering structures 280 a and 280b on the substrate 120 is, for example, in a range between 0.5 and 0.9,such that the buffering structures 280 a and 280 b can provide a widerrange of buffer without affecting subsequent picking-up process.

In the embodiment, the material of the holding structure 260 isdifferent from the material of the buffering structures 280 a and 280 b,and the Young's modulus of the holding structure 260 is larger than theYoung's modulus of the buffering structures 280 a and 280 b, such thatthe buffering structures 280 a and 280 b have buffering function.Herein, the material of the holding structure 260 is, for example, aninorganic material, and the material of the buffering structures 280 aand 280 b is, for example, an organic material.

As shown in FIG. 2A, the orthogonal projection of the bufferingstructures 280 a and 280 b on the substrate 120 does not overlap theorthogonal projection of the micro device 140 on the substrate 120.Therefore, the buffering structures 280 a and 280 b can absorb theexternal force that is applied to the holding structure 260 when holdingthe micro device 140 in the delivering and transferring process, therebyimproving the yield rate of delivery and transfer without affecting thepicking-up yield rate of the micro device 140. Preferably, theorthogonal projection of the buffering structures 280 a and 280 b on thesubstrate 120 is spaced apart from the orthogonal projection of themicro device 140 on the substrate 120 by a smallest distance L3. Thesmallest distance L3 may be smaller than or equal to 10 μm, theinvention provides no limitation thereto.

Additionally, as shown in FIG. 2B, there is an air gap G1 between theholding structure 260, the substrate 120, the micro device 140 and thebuffering structures 280 a and 280 b in the embodiment. Herein, theconnecting portions 262 a and 262 b of the holding structure 260 do notcompletely cover the peripheral surface 143 of the micro device 140. Avertical distance H1 between the micro device 140 and the substrate 120is designed based on the height of the micro device 140. Preferably, thevertical distance H1 is larger than 0 and smaller than 0.5 times theheight of the micro device 140. If the vertical distance H1 is largerthan 0.5 times the height of the micro device 140, the height differenceof the holding structure 260 is too large, as a result, the holdingstructure is difficult to be manufactured and might be broken easily.Generally speaking, the vertical distance H1 is in a range between 0.1μm and 5 μm.

FIG. 3 is a schematic top view of a structure with micro deviceaccording to a third embodiment of the invention. A structure with microdevice 300 in the embodiment is similar to the structure with microdevice 100 in the first embodiment, and the difference between the twois that the outer contours of connecting portions 362 a and 362 b of aholding structure 360 in the embodiment are linear contours.

Specifically, from the top view direction, the shape constructed by acovering portion 363, the connecting portions 362 a and 362 b andholding portions 361 a and 361 b is, for example, a dumbbell shape. Theholding structure 360 is continuously connected to the top surface 141of the micro device 140, and the width change of the covering portion363 from the connecting portions 362 a and 362 b to the center 141P ofthe top surface 141 of the micro device 140 is gradually decreased atfirst and then becomes consistent. In this manner, in the exposure andetching process for forming the holding structure 360, even if a slightshift is occurred unexpectedly, for example, a shift in the directionD1, the holding structure 360 can still be disposed on the top surface141 of the micro device 140 without being shifted to other position, andthe connecting portions 362 a and 362 b of the holding structure 360 canhave the narrowest width between the edges SD1 and SD3 of the microdevice 140 and the holding portions 361 a and 361 b (i.e., the smallestwidths W1, W2), thereby enhancing the process window of the holdingstructure 360.

FIG. 4A is a schematic top view of a structure with micro deviceaccording to a fourth embodiment of the invention. FIG. 4B is aschematic cross-sectional view of the structure with micro device inFIG. 4A. It should be indicted that a structure with micro device 400 inFIG. 4B is illustrated along line C-C′ of FIG. 4A. The structure withmicro device 400 in the embodiment is similar to the structure withmicro device 200 of the second embodiment, and the difference betweenthe two is that a first-type electrode 444 and a second-type electrode445 of a micro device 440 of the embodiment are disposed on the samesurface. Herein, the first-type electrode 444 and the second-typeelectrode 445 of the micro device 440 are disposed on a bottom surface442. The shape of a holding structure 460 is, for example, a strapshape. Specifically, from the top view direction, the holding structure460 is continuously connected to the top surface 441 of the micro device440, and the central width W3 of a covering portion 463 is larger thanwidths (i.e., smallest widths W1, W2) of the connecting portions 462 aand 462 b on the corresponding edges SD1 and SD3 of the top surface 441.Herein, preferably, a ratio of the orthogonal projection area of theholding structure 460 on the top surface 441 of the micro device 440 toa surface area of the top surface 441 of the micro device 440 is largerthan or equal to 0.5 and smaller than 1. Preferably, a ratio of theorthogonal projection area of the holding structure 460 on the topsurface 441 of the micro device 440 to the surface area of the topsurface 441 of the micro device 440 is larger than 0.7 and smallerthan 1. It should be pointed out that, since the covering portion 463 ofthe holding structure 460 in the embodiment is distributed on nearly theoverall top surface 441 of the micro device 440, the flatness of themicro device 440 can be increased in subsequent transfer process.

FIG. 5 is a schematic top view of a structure with micro deviceaccording to a fifth embodiment. A structure with micro device 500 inthe embodiment is similar to the structure with micro device 100 in thefirst embodiment, and the difference between the two is that each ofholding structures 560 of the embodiment has two covering portions 563 aand 563 b separated from each other. In other words, the structure ofthe covering portions 563 a and 563 b of the embodiment is anon-continuous structure.

More specifically, the two covering portions 563 a and 563 b of theholding structure 560 are respectively disposed on two opposite edgesSD1 and SD3, and a connecting portion 562 a has the smallest width W1 atthe corresponding edge SD2 of the top surface 141 of the micro device140, and a connecting portion 562 b has the smallest width W2 at thecorresponding edge SD4 of the top surface 141 of the micro device 140.The width change of the covering portions 563 a and 563 b from thecorresponding connecting portions 562 a and 562 b to the center 141P ofthe top surface 141 of the micro device 140 is gradually decreased,thereby improving the process window of the holding structure 560.

From the top view direction, the holding structure 560 does not overlapthe center 141P of the top surface 141 of the micro device 140, and thesmallest distances L1 from the center 141P of the top surface 141 of themicro device 140 to each of the covering portions 563 a and 563 b may bethe same, the invention provides no limitation thereto. Preferably, thedistances L1 from the center 141P of the top surface 141 of the microdevice 140 to each of the covering portions 563 a and 563 b may besmaller than or equal to the lengths of half of the edges SD2 and SD4,such that a better holding force can be attained, the invention providesno limitation thereto. Additionally, as shown in FIG. 5 , a largestdistance L2 is formed from each of the covering portions 563 a and 563 bto the edges SD1 and SD3 of the top surface 141 of the micro device 140.Preferably, a ratio of the largest distance L2 to the lengths of theedges SD1 and SD3 is smaller than or equal to 0.2. When the ratio islarger than 0.2, the holding force is too large, which affectssubsequent picking-up and transferring processes. It should be indicatedthat the largest distance L2 may be smaller than or equal to 10 μm.

FIG. 6A is a schematic top view of a structure with micro deviceaccording to a sixth embodiment of the invention. FIG. 6B is a schematiccross-sectional view of the structure with micro device in FIG. 6A. Itshould be indicated that FIG. 6B is illustrated along line D-D′ of FIG.6A. A structure with micro device 600 of the embodiment is similar tothe structure with micro device 500 of the fifth embodiment, and thedifference between the two is that a holding structure 660 of theembodiment is partially disposed on a top surface 641. Morespecifically, from a top view, a micro device 640 of the embodiment hasa first lateral side S1 and a second lateral side S2 adjacent to eachother. A length L4 of the first lateral side S1 is smaller than a lengthL5 of the second lateral side S2. Connecting portions 662 a and 662 band covering portions 663 a and 663 b of the holding structure 660 arerespectively disposed on the opposite first lateral side S1, that is,the holding structure 660 is disposed on a relatively shorter side ofthe micro device 640. With the configuration that the holding structure660 is disposed on the relatively shorter side of the micro device 640,the micro device 640 can be arranged more intensively, thereby reducingthe manufacturing cost of the micro device 640. It should be pointed outthat, as shown in FIG. 6B, the holding structure 660 is not coplanar.Specifically, the connecting portions 662 a and 662 b as well as thecovering portions 663 a and 663 b of the holding structure 660 are notin coplanar, thereby avoiding that the holding structure 660 is disposedon the height difference of the micro device 640 and increasing theprocess window of manufacturing process.

Additionally, the structure with micro device 600 of the embodimentfurther includes at least one buffering structure (a plurality ofbuffering structures 680 a, 680 b, 680 c are exemplified in FIG. 6 ).The buffering structures 680 a, 680 b and 680 c are disposed between theholding structure 660 and the substrate 120 such that the holdingstructure 660 is connected to the substrate 120 through the bufferingstructures 680 a, 680 b and 680 c. In the embodiment, the configurationof the buffering structures 680 a, 680 b and 680 c may be the same as orsimilar to the configuration of the buffering structure (e.g., bufferingstructures 280 a, 280 b in the second embodiment) in the foregoingembodiment, and related descriptions are omitted hereinafter.

FIG. 7 is a schematic top view of a structure with micro deviceaccording to a seventh embodiment of the invention. A structure withmicro device 700 of the embodiment is similar to the structure withmicro device 100 of the first embodiment, and the difference between thetwo is that a covering portion 763 of a holding structure 760 in theembodiment has a plurality of inflection points 763 p, and the widthchange of the covering portion 763 is gradually increased from theinflection points 763 p to the connecting portions 162 a and 162 b. Inother words, the covering portion 763 of the holding structure 760 has asmallest width W4 at the position of the inflection points 763 p.Preferably, the central width W3 of the covering portion 763 is largerthan widths (i.e., smallest widths W1, W2) of the connecting portions162 a and 162 b at the corresponding edges SD1 and SD3 of the topsurface 641, such that the first-type electrode 644 can be avoided andthe covering portion 763 can be distributed on the overall top surface641 of the micro device 140, thereby increasing flatness of the microdevice 140 in subsequent transferring process. With the inflectionpoints 763 p, in the exposure and etching process for forming theholding structure 760, even if a slight shift is occurred unexpectedly,the holding structure 760 can still be disposed on the top surface 641of the micro device 140 without being shifted to other position, and theconnecting portions 162 a and 162 b of the holding structure 760 canhave the narrowest width (i.e., smallest widths W1, W2) at the edges SD1and SD3 of the micro device 140, thereby increasing the process windowof the holding structure 760. It should be pointed out that the holdingstructure 760 herein passes through a center 641P of the top surface 641such that the holding structure 760 can hold the micro device 140 morefirmly.

FIG. 8 is a schematic top view of a structure with micro deviceaccording to an eighth embodiment of the invention. A structure withmicro device 800 of the embodiment is similar to the structure withmicro device 400 of the fourth embodiment, and the difference betweenthe two is that each of holding structures 860 of the embodiment has aplurality of connecting portions (four connecting portions 862 a, 862 b,862 c, 862 d are exemplified in FIG. 8 ), and the connecting portions862 a, 862 b, 862 c, 862 d are extended from corners C1, C2, C3, C4 of amicro device 840 and connected between a covering portion 863 and aholding portion 861.

From the top view direction, the connecting portions 862 a, 862 b, 862c, 862 d are respectively directly in contact with the four corners C1,C2, C3, C4 of the top surface 841 of the micro device 840. Specifically,the connecting portion 862 a is directly in contact with the corner C1of the top surface 841 and connected to the holding portion 861 and thecovering portion 863. The connecting portion 862 b is directly incontact with the corner C2 of the top surface 841 and connected to theholding portion 861 and the covering portion 863. The connecting portion862 c is directly in contact with the corner C3 of the top surface 841and connected to the holding portion 861 and the covering portion 863.The connecting portion 862 d is directly in contact with the corner C4of the top surface 841 and connected to the holding portion 861 and thecovering portion 863. It should be indicated that, in the embodiment,the connecting portions 862 a, 862 b, 862 c, 862 d of the holdingstructure 860 are disposed at opposite corners of the top surface 841 ofthe micro device 840. In this manner, the space required for configuringa plurality of holding structures 860 can be saved, and the plurality ofmicro devices 840 can be arranged intensively, thereby reducing cost. Itshould be indicated that, in other embodiments that are not shown, theinvention provides no limitation to the number of the corner of themicro device for configuring the holding structure. As long as thecorner of the top surface of the micro device for configuring theholding structure allows the plurality of micro devices to be arrangedintensively, it belongs the scope to be claimed in the invention.

FIG. 9 is a schematic top view of a structure with micro deviceaccording to a ninth embodiment of the invention. A structure with microdevice 900 of the embodiment is similar to the structure with microdevice 800 in the eighth embodiment, and the difference between the twois that each of the holding structures 960 of the structure with microdevice 900 of the embodiment has two connecting portions 962 a and 962b. The connecting portion 962 a is directly in contact with the cornerC2 of the top surface 841 of the micro device 840 and connected to theholding portion 861 and the covering portion 863, and the connectingportion 962 b is directly in contact with the corner C4 of the topsurface 841 and connected to the holding portion 861 and the coveringportion 863.

FIG. 10 is a schematic cross-sectional view of a structure with microdevice according to a tenth embodiment of the invention. Referring toFIG. 1B and FIG. 10 , a structure with micro device 1000 of theembodiment is similar to the structure with micro device 100 of thefirst embodiment, and the difference between the two is that a bufferinglayer 170 is provided between the structures with micro device 1000 ofthe embodiment. In other words, there may be no air space between themicro device 140, a holding structure 1060 and the substrate 120 of theembodiment. Herein, a holding portion 1061 of the holding structure 1060is directly in contact with the substrate 120, and a connecting portion1062 of the holding structure 1060 is directly in contact with theperipheral surface 143 of the micro device 140. The buffering layer 170is directly in contact with the holding structure 1060 and the microdevice 140. The buffering layer 170 can absorb the stress generated whenthe micro device 140 is bonded to the substrate 120, thereby increasingthe bonding yield rate. In other words, the buffering layer 170 canachieve the effect of buffering the stress between the micro device 140and the substrate 120. Preferably, the Young's modulus of the bufferinglayer 170 is smaller than the Young's modulus of the holding structure1060. Herein, the material of the buffering layer 170 includes a foammaterial or an organic polymer material, such that the buffering layer170 has a plurality of irregular air pores, wherein the porosity of thebuffering layer 170 constructed by the foam material may be larger thanor equal to 50%, thereby providing a good buffering effect.

FIG. 11 is a schematic cross-sectional view of a structure with microdevice according to an eleventh embodiment of the invention. Referringto FIG. 10 and FIG. 11 , a structure with micro device 1100 of theembodiment is similar to the structure with micro device 1000 of thetenth embodiment, and the difference between the two is that aconnecting portion 1162 of a holding structure 1160 of the structurewith micro device 1100 of the embodiment is not directly in contact withthe peripheral surface 143 of the micro device 140.

FIG. 12 is a schematic cross-sectional view of a structure with microdevice according to a twelfth embodiment of the invention. Referring toFIG. 11 and FIG. 12 , a structure with micro device 1200 of theembodiment is similar to the structure with micro device 1100 in theeleventh embodiment, and the difference between the two is that aholding portion 1261 of a holding structure 1260 of the embodiment isfurther extended and covers a portion of the bottom surface 142 of themicro device 140. In other words, the holding portion 1261 of theholding structure 1260 is extended to be in contact with the bottomsurface 142 of the micro device 140.

FIG. 13 is a schematic cross-sectional view of a structure with microdevice according to a thirteenth embodiment of the invention. Referringto FIG. 11 and FIG. 13 , a structure with micro device 1300 of theembodiment is similar to the structure with micro device 1100 in theeleventh embodiment, and the difference between the two is that aholding portion 1361 of a holding structure 1360 of the embodiment isfurther extensively disposed on a portion of the bottom surface 142 ofthe micro device 140. In other words, the holding portion 1361 of theholding structure 1360 is extended to be in contact with the bottomsurface 142 of the micro device 140.

FIG. 14 is a schematic cross-sectional view of a structure with microdevice according to a fourteenth embodiment of the invention. Referringto FIG. 11 and FIG. 14 , a structure with micro device 1400 of theembodiment is similar to the structure with micro device 1100 of theeleventh embodiment, and the difference between the two is that aholding portion 1461 of a holding structure 1460 of the embodiment isnot aligned with the peripheral surface 143 of the micro device 140. Inother words, the orthogonal projection of the micro device 140 on thesubstrate 120 does not overlap the orthogonal projection of the holdingportion 1461 of the holding structure 1460 on the substrate 120.

FIG. 15 is a schematic cross-sectional view of a structure with microdevice according to a fifteenth embodiment of the invention. Referringto FIG. 11 and FIG. 15 , a structure with micro device 1500 of theembodiment is similar to the structure with micro device 1100 of theeleventh embodiment, and the difference between the two is that aconnecting portion 1562 of a holding structure 1560 of the embodimentdoes not completely cover the peripheral surface 143 of the micro device140. In other words, the connecting portion 1562 of the holdingstructure 1560 only covers a portion of the peripheral surface 143;therefore, the orthogonal projection of the micro device 140 on thesubstrate 120 does not overlap the orthogonal projection of theconnecting portion 1562 of the holding structure 1560 on the substrate120.

FIG. 16 is a schematic cross-sectional view of a structure with microdevice according to a sixteenth embodiment of the invention. Referringto FIG. 10 and FIG. 16 , a structure with micro device 1600 of theembodiment is similar to the structure with micro device 1000 of thetenth embodiment, and the difference between the two is that coveringportions 1663 a and 1663 b of a holding structure 1660 of the embodimentare plural and separated from each other.

FIG. 17 is a schematic cross-sectional view of a structure with microdevice according to a seventeenth embodiment of the invention. Referringto FIG. 10 and FIG. 17 , a structure with micro device 1700 of theembodiment is similar to the structure with micro device 1000 of thetenth embodiment, and the difference between the two is that, in theembodiment, two adjacent micro devices 140 and 140′ are connectedtogether through holding portions 1761 and 1761′ of holding structures1760 and 1760′. In the embodiments that are not shown, the holdingportions 1761 and 1761′ may not be connected together, the invention isnot limited thereto.

FIG. 18 is a schematic cross-sectional view of a structure with microdevice according to an eighteenth embodiment of the invention. Referringto FIG. 10 and FIG. 18 , a structure 1800 with micro device of theembodiment is similar to the structure with micro device 1000 of thetenth embodiment, and the difference between the two is that thestructure with micro device 1800 of the embodiment respectively furtherincludes a plurality of buffering structures 1880 and 1880′, wherein theholding structures 1860 and 1860′ of the micro devices 140 and 140′ arerespectively connected to the substrate 120 through the bufferingstructures 1880 and 1880′, and the two adjacent micro devices 140 and140′ are connected together through the holding portions 1861 and 1861′of the holding structures 1860 and 1860′.

FIG. 19 is a schematic cross-sectional view of a structure with microdevice according to a nineteenth embodiment of the invention. Referringto FIG. 4B and FIG. 19 , a micro device 940 of the structure with microdevice 1900 of the embodiment includes a first-type semiconductor layer947, a light emitting layer 946, a second-type semiconductor layer 948,an insulating layer 949, a through hole T, a first-type electrode 944and a second-type electrode 945. Specifically, the through hole Tpenetrates through the second-type semiconductor layer 948, the lightemitting layer 946 and a portion of the first-type semiconductor layer947 in sequence. The insulating layer 949 covers the peripheral surface943, a portion of the bottom surface 942 and the inner wall of thethrough hole T. The holding structure 1960 is directly in contact withthe top surface 941 and the insulating layer 949 disposed on theperipheral surface 943. The first-type electrode 944 and the second-typeelectrode 945 are disposed on the bottom surface 942, and the first-typeelectrode 944 is filled in the through hole T and electrically connectedto the first-type semiconductor layer 947, and the second-type electrode945 passes through the insulting layer 949 of the bottom surface 942 andelectrically connected to the second-type semiconductor layer 948.

More specifically, in the embodiment, the material of the holdingstructure 1960 is different from the material of the insulating layer949. Herein, the material of the insulating layer 949 is, for example,silicon dioxide, silicon nitride, spin on glass (SOG) or similarmaterial, the invention is not limited thereto. Preferably, the hardnessof the holding structure 1960 is equal to or lower than the hardness ofthe insulating layer 949, and the thickness of the holding structure1960 is smaller than or equal to the thickness of the insulating layer949. In this manner, it can be avoided that the holding structure 1960and the insulting layer 949 are removed simultaneously when the microdevice 940 is transferred. Additionally, in the embodiment, the centerof gravity of the holding structure 1960 is lower than the center ofgravity of the micro device 940, and the holding structure 1960 on thetop surface 941 of the micro device 940 has an angle that is the same asthe angle of the holding structure 1960 on the peripheral surface 943,such that the micro device 940 can be fixed on the substrate 120 moreeffectively.

It should also be indicated that, when the micro devices 140, 140′, 440,640, 840 and 940 of the structures with micro device 100, 200, 300, 400,500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700,1800 and 1900 are picked up from the substrate 120 and delivered andtransferred to be placed on a circuit substrate 2020 (refer to FIG. 20), only a portion of the holding structures 160, 260, 360, 460, 560,660, 760, 860, 960, 1060, 1160, 1260, 1360, 1460, 1560, 1660, 1760,1760′, 1860, 1860′ and 1960 still cover the top surfaces 141, 441, 641,841 and 941 or a portion of the peripheral surfaces 143 and 943 of themicro devices 140, 140′, 440, 640, 840 and 940, related embodiments areprovided below.

FIG. 20 is a schematic cross-sectional view of a structure with microdevice transferred to a circuit substrate according to an embodiment ofthe invention. Referring to FIG. 20 , a plurality of micro devices 140are transferred to the circuit substrate 2020 to form an apparatus withmicro device 2000. The apparatus with micro device 2000 is, for example,a micro LED display or other electronic facility having display. Herein,the micro device 140 is shown as a flip-chip micro LED and may be an LEDhaving same color light or an LED having different color light, theinvention provides no limitation thereto. In other words, the microdevice 140 is electrically connected to the circuit substrate 2020 inthe flip-chip manner. The holding structure that is originally disposedon the top surface 141 of the micro device 140 may remain only aportion, i.e., a light guide structure 2050, after the micro device 140is picked up. In some embodiments that are not shown, the light guidestructure may be simultaneously disposed on the top surface and aportion of peripheral surface of the micro device. Herein, the circuitsubstrate 2020 may be, for example, a display back panel or othersubstrate having circuit.

FIG. 21 is a schematic cross-sectional view of a structure with microdevice transferred to a circuit substrate according to anotherembodiment of the invention. Referring to FIG. 20 and FIG. 21 , anapparatus with micro device 2100 of the embodiment is similar to theapparatus with micro device 2000 in FIG. 20 , and the difference betweenthe two is that the apparatus with micro device 2100 of the embodimentfurther includes a light guide layer 2110. Specifically, the light guidelayer 2110 is disposed on the micro device 140, and a light guidestructure 2050 and the micro device 140 are respectively disposed on twoopposite sides of the light guide layer 2110, wherein the light guidelayer 2110 is directly in contact with the top surface 141 of the microdevice 140. Preferably, the light guide layer 2110 is conformallydisposed on the micro device 140, and the light guide structure 2050 isconformally disposed on the light guide layer 2110.

In the embodiment, the reflective index of the micro device 140 may belarger than the reflective index of the light guide layer 2110, and/orthe reflective index of the light guide layer 2110 may be larger than orequal to the reflective index of the light guide structure 2050. In thismanner, it can be avoided that the light emitted by the micro device 140generates total reflection on the interface between the light guidelayer 2110 and the micro device 140 and/or on the interface between thelight guide structure 2050 and the light guide layer 2110, therebyimproving light output ratio of the micro device 140. Herein, thematerial of the light guide layer 2110 may be different from thematerial of the micro device 140 of the light guide structure 2050,wherein the material of the light guide layer 2110 is, for example,silicon dioxide, silicon nitride, spin on glass (SOG) or a combinationthereof, the invention is not limited thereto. Additionally, the Young'smodulus of the light guide layer 2110 of the embodiment is smaller thanthe Young's modulus of the micro device 140. The orthogonal projectionarea of the light guide structure 2050 on the top surface 141 of themicro device 140 is equal to the orthogonal projection area of the lightguide layer 2110 on the top surface 141, the invention is not limitedthereto.

FIG. 22 is a schematic cross-sectional view of a structure with microdevice transferred to a circuit substrate according to still anotherembodiment of the invention. Referring to FIG. 21 and FIG. 22 , anapparatus with micro device 2200 in the embodiment is similar to theapparatus with micro device 2100 in FIG. 21 , and the difference betweenthe two is that the orthogonal projection area of a light guidestructure 2250 of the apparatus with micro device 2200 on the topsurface 141 of the embodiment is smaller than the orthogonal projectionarea of the light guide layer 2110 on the top surface 141. Preferably, aratio of the orthogonal projection area of the light guide structure2250 on the top surface 141 to the orthogonal projection area of thelight guide layer 2110 on the top surface 141 is in the range between0.8 and 1.

FIG. 23A is a schematic three-dimensional view of a micro deviceaccording to an embodiment of the invention. FIG. 23B is a schematicside view of the micro device in FIG. 23A. Referring to FIG. 23A andFIG. 23B, a micro device 10 a includes an epitaxial structure 12 and alight guide structure 14 a. The epitaxial structure 12 has a top surface13. The light guide structure 14 a is disposed on the top surface 13,and the light guide structure 14 a includes a connecting portion 15 aand a covering portion 17 a. The connecting portion 15 a is disposed onan edge 11 a of the epitaxial structure 12 and extends along a sidewall11 b of the epitaxial structure 12. The covering portion 17 a isdisposed on the top surface 13 and connected to the connecting portion15 a. Herein, the light guide structure 14 a is arranged along thediagonal of the top surface 13. From the direction A1, a width W11 ofthe connecting portion 15 a at the edge 11 a of the epitaxial structure12 is smaller than a width W12 away from the top surface 13.

In more detail, the width W10 of the connecting portion 15 a away fromthe top surface 13 gradually increase, which can increase the sidelight-emitting efficiency of the micro device 10 a. Herein, an outercontour of the connecting portion 15 a is, for example, a curvedcontour, so that the micro device 10 a has a better light profile. Sincethe width W11 of the connecting portion 15 a at the edge 11 a of theepitaxial structure 12 is smaller than the width W12 away from the topsurface 13 thereby improving the side light-emitting efficiency of themicro device 10 a. Therefore, in addition to the covering portion 17 athat can effectively raise the forward light-emitting efficiency of themicro device 10 a, the connecting portion 15 a can also raise the sidelight-emitting efficiency of the micro device 10 a, thereby improvingthe light-emitting efficiency of the micro device 10 a.

FIG. 24 is a schematic top view of a micro device according to anembodiment of the invention. Referring to both FIG. 23A and FIG. 24 , amicro device 10 b provided in the embodiment is similar to the microdevice 10 a depicted in FIG. 23A, and the difference therebetween is asfollows: the light guide structure 14 b is arranged along the oppositesides of the top surface 13. A central width W21 of the covering portion17 b is larger than a width W22 of the connecting portion 15 b on thecorresponding edge 11 a of the top surface 13, so that at the middle ofthe covering portion 17 b has a better light guiding efficiency. In moredetail, the covering portion 17 b of the light guide structure 14 b hasa plurality of inflection points P, and a width of the covering portion17 b is gradually increased from the inflection points P to theconnecting portion 15 b. In other words, the covering portion 17 b has asmallest width W23 at the position of the inflection points P.

FIG. 25A is a schematic top view of a micro device according to anotherembodiment of the invention. FIG. 25B is a schematic side view of themicro device in FIG. 25A. Referring to both FIG. 23A, FIG. 25A and FIG.25B, a micro device 10 c provided in the embodiment is similar to themicro device 10 a depicted in FIG. 23A, and the difference therebetweenis as follows: the light guide structure 14 c is arranged along theopposite sides of the top surface 13. A central width W31 of thecovering portion 17 c is smaller than a width W32 of the connectingportion 15 c on the corresponding edge 11 a of the top surface 13, sothat at the side of the top surface 13 has a better light guidingefficiency. From the direction A2, a width of the covering portion 17 cof the light guide structure 14 c is gradually increased toward theconnecting portion 15 c of the light guide structure 14 c.

FIG. 26A is a schematic top view of a micro device according to anotherembodiment of the invention. FIG. 26B is a schematic side view of themicro device in FIG. 26A. Referring to both FIG. 23A, FIG. 26A and FIG.26B, a micro device 10 d provided in the embodiment is similar to themicro device 10 a depicted in FIG. 23A, and the difference therebetweenis as follows: from the top view direction, the covering portion 17 d ofthe light guide structure 14 d is continuously connected to the topsurface 13 of the epitaxial structure 12, and the central width W41 ofthe covering portion 17 d is larger than width W42 of the connectingportions 15 d on the corresponding edge 11 a of the top surface 13.Herein, preferably, a ratio of the orthogonal projection area of thecovering portion 17 d on the top surface 13 of the epitaxial structure12 to a surface area of the top surface 13 of the epitaxial structure 12is larger than or equal to 0.5 and smaller than 1. Preferably, a ratioof the orthogonal projection area of the covering portion 17 d on thetop surface 13 of the epitaxial structure 12 to the surface area of thetop surface 13 of the epitaxial structure 12 is larger than 0.8 andsmaller than 1. Form the direction A3, the width W42 of the connectingportion 15 d away from the top surface 13 gradually increase, which canincrease the side light-emitting efficiency of the micro device 10 d.

FIG. 27A is a schematic cross-sectional view of a micro device accordingto an embodiment of the invention. FIG. 27A is viewed from a directionA4 of FIG. 26A, wherein the direction A4 is perpendicular to thedirection A3. Referring to both FIG. 26A and FIG. 27A, a micro device 10e provided in the embodiment is similar to the micro device 10 ddepicted in FIG. 26A, and the difference therebetween is as follows: thecovering portion 17 e of the light guide structure 14 e has a patternedsurface 18, and the connecting portion 15 e of the light guide structure14 e has a flat surface 16, so the forward light-emitting efficiency ofthe micro device 10 e can be increased, and the sidewall yield can beprevented from being reduced. In more detail, the connecting portion 15e directly contacts the sidewall 11 b of the epitaxial structure 12.Furthermore, a ratio of a vertical height T1 of the connecting portion15 e to a vertical height T of the epitaxial structure 12 is less thanor equal to 0.3. In addition, a ratio of a horizontal width M1 of theconnecting portion 15 e to a horizontal width M of the epitaxialstructure 12 is less than or equal to 0.3. If the ratio of the verticalheight and the ratio of the horizontal width described above arerespectively too large, it will affect the process yield of the microdevice 10 e.

FIG. 27B is a schematic cross-sectional view of a micro device accordingto an embodiment of the invention. Referring to both FIG. 27A and FIG.27B, a micro device 10 e′ provided in the embodiment is similar to themicro device 10 e depicted in FIG. 27A, and the difference therebetweenis as follows: the epitaxial structure 12 e comprises a first-typesemiconductor layer 12 e 1, a second-type semiconductor layer 12 e 2 anda light-emitting layer 12 e 3. The first-type semiconductor layer 12 e 1has the top surface 13. The light-emitting layer 12 e 3 is locatedbetween the first-type semiconductor layer 12 e 1 and the second-typesemiconductor layer 12 e 2. The top surface 13 of the first-typesemiconductor layer 12 e 1 is relatively far from the light-emittinglayer 12 e 3, and the connecting portion 15 e of the light guidestructure 14 e′ directly covers a peripheral surface of the first-typesemiconductor layer 12 e 1 and a peripheral of the light-emitting layer12 e 3, so that the light guide structure 14 e′ can help the sidelight-emitting efficiency, but the invention is not limited thereto. Thecovering portion 17 e′ of the light guide structure 14 e has a flatsurface 18.

FIG. 28 is a schematic cross-sectional view of a micro device accordingto an embodiment of the invention. Referring to both FIG. 27B and FIG.28 , a micro device 10 f provided in the embodiment is similar to themicro device 10 e depicted in FIG. 27A, and the difference therebetweenis as follows: the connecting portion 15 f of the light guide structure14 f does not contact the sidewall 11 b of the epitaxial structure 12,the covering portion 17 f of the light guide structure 14 f has a flatsurface 18′. Since the connecting portion 15 f does not contact thesidewall 11 b of the epitaxial structure 12, it could reduce the damageof the micro device 10 e.

FIG. 29 is a schematic cross-sectional view of a micro device accordingto an embodiment of the invention. Referring to both FIG. 28 and FIG. 29, a micro device 10 g provided in the embodiment is similar to the microdevice 10 f depicted in FIG. 28 , and the difference therebetween is asfollows: the micro device 10 g further comprises a light guide layer 19connected to the top surface 13 of the epitaxial structure 12. An areaof the light guide layer 19 is less than or equal to an area of the topsurface 13 of the epitaxial structure 12. Preferably, the aforementionedratio is greater than 0.8 and less than or equal to 1. In other words,light guide layer 19 can be completely disposed on the top surface 13 toincrease light guide. Herein, the area of the light guide layer 19 onthe top surface 13 of the epitaxial structure 12 is larger than an areaof the light guide structure 14 g on the light guide layer 19. The areaof the light guide structure 14 g is less than or equal to the area ofthe light guide layer 19 which can concentrate the light. In particular,the refractive index of the epitaxial structure 12 is greater than therefractive index of the light guide layer 19 and is greater than therefractive index of the light guide structure 14 g, which can increasethe light output and avoid total reflection.

FIG. 30 is a schematic cross-sectional view of a micro device displayapparatus according to an embodiment of the invention. Referring to FIG.30 , a micro device display apparatus 1 includes a circuit substrate 2and at least one micro device 10 a′ (three micro devices 10 a′ areexemplified in FIG. 30 ). The micro device 10 a′ are separately disposedon the circuit substrate 2. Each of the micro devices 10 a iselectrically connected to the pads 21 of the circuit substrate 2 by theelectrodes E. The electrodes E have different electrical properties,that is, this structure is a flip chip. However, in the unillustratedembodiment, the electrodes E can also have the same electrode property,that is, the structure is a vertical chip. Herein, the micro devices 10a′ are shown as the flip-chip micro LEDs and may be having the samecolor light or having different color light, the invention provides nolimitation thereto. In other words, the micro devices 10 a areelectrically connected to the circuit substrate 2 in the flip-chipmanner. In addition, the circuit substrate 2 may be, for example, adisplay back panel or other substrate having circuit.

In summary, in the design of the structure with micro device of theinvention, from the top view direction, the connecting portion of theholding structure is extended along a horizontal direction and connectedbetween the covering portion and the holding portion, and the widthchange of the connecting portion is gradually increased from the edge orcorner of the micro device to the holding portion. That is to say, theconnecting portion of the holding structure may have the narrowest widthat the edge or in the corner of the micro device. With such design, whenthe micro device is delivered and transferred between differenttemporary substrates, it can be controlled that the breaking point ofthe holding structure can be as close to the edge or corner of the microdevice as possible, thereby reducing the problem that the holdingstructure is not completely broken or remained, such that the yield rateof delivery and transfer of the micro LED can be improved.

In addition, the connecting portion of the light guide structure isdisposed on the edge of the epitaxial structure and extending along thesidewall of the epitaxial structure. In particular, the width of theconnecting portion at the edge of the epitaxial structure is smallerthan the width away from the top surface, thereby improving the sidelight-emitting efficiency of the micro device. Therefore, in addition tothe covering portion that can effectively raise a forward light-emittingefficiency of the micro device, the connecting portion can also raise aside light-emitting efficiency of the micro device, thereby improvingthe light-emitting efficiency of the micro device.

Although the invention has been disclosed by the above embodiments, theembodiments are not intended to limit the invention. It will be apparentto those skilled in the art that various modifications and variationscan be made to the structure of the invention without departing from thescope or spirit of the invention. Therefore, the protecting range of theinvention falls in the appended claims.

What is claimed is:
 1. A micro device, comprising: an epitaxialstructure having a top surface; and a light guide structure disposed onthe top surface, and the light guide structure comprising: a connectingportion disposed on an edge of the epitaxial structure and extendingalong a sidewall of the epitaxial structure; and a covering portiondisposed on the top surface and connected to the connecting portion,wherein a width of the connecting portion at the edge of the epitaxialstructure is smaller than a width away from the top surface.
 2. Themicro device according to claim 1, wherein the width of the connectingportion away from the top surface gradually increases.
 3. The microdevice according to claim 1, wherein an outer contour of the connectingportion is a curved contour.
 4. The micro device according to claim 1,wherein a central width of the covering portion is larger than a widthof the connecting portion on the corresponding edge of the top surface.5. The micro device according to claim 4, wherein the covering portionhas a plurality of inflection points, and a width of the coveringportion is gradually increased from the inflection points to theconnecting portion.
 6. The micro device according to claim 1, wherein acentral width of the covering portion is smaller than a width of theconnecting portion on the corresponding edge of the top surface.
 7. Themicro device according to claim 6, wherein a width of the coveringportion is gradually increased toward the connecting portion.
 8. Themicro device according to claim 1, further comprising: a light guidelayer connected to the top surface of the epitaxial structure, whereinan area of the light guide layer is less than or equal to an area of thetop surface of the epitaxial structure, and the area of the light guidelayer on the top surface of the epitaxial structure is larger than anarea of the light guide structure on the light guide layer.
 9. The microdevice according to claim 1, wherein the connecting portion does notcontact the sidewall of the epitaxial structure.
 10. The micro deviceaccording to claim 1, wherein the covering portion has a patternedsurface, and the connecting portion has a flat surface.
 11. The microdevice according to claim 1, wherein a ratio of a vertical height of theconnecting portion to a vertical height of the epitaxial structure isless than or equal to 0.3.
 12. The micro device according to claim 1,wherein a ratio of a horizontal width of the connecting portion to ahorizontal width of a epitaxial structure is less than or equal to 0.3.13. The micro device according to claim 1, wherein the epitaxialstructure comprises: a first-type semiconductor layer having the topsurface; a second-type semiconductor layer; and a light-emitting layerlocated between the first-type semiconductor layer and the second-typesemiconductor layer, wherein the top surface of the first-typesemiconductor layer is relatively far from the light-emitting layer, andthe connecting portion directly covers a peripheral surface of thefirst-type semiconductor layer and a peripheral of the light-emittinglayer.
 14. A micro device display apparatus, comprising: a circuitsubstrate; and at least one micro device disposed on the circuitsubstrate, and the at least one micro device comprising: an epitaxialstructure having a top surface; and a light guide structure disposed onthe top surface, and the light guide structure comprising: a connectingportion disposed on an edge of the epitaxial structure and extendingalong a sidewall of the epitaxial structure; and a covering portiondisposed on the top surface and connected to the connecting portion,wherein a width of the connecting portion at the edge of the epitaxialstructure is smaller than a width away from the top surface.